Add onboarding screen + token check

context/AppProvider.tsx

@@ -0,0 +1,31 @@
+import {createContext, PropsWithChildren, useContext} from "react";
+import {useStorageState} from '@/context/UseStorageState';
+
+type TokenType = {
+  token: string | null;
+  setToken: (token: string | null) => void;
+  isLoading: boolean;
+}
+
+const TokenContext = createContext<TokenType>({
+  setToken: () => {
+  },
+  token: null,
+  isLoading: true,
+});
+
+export const useToken = () => useContext(TokenContext);
+
+export function AppProvider({ children }: PropsWithChildren) {
+  const [[isLoading, token], setSession] = useStorageState('appToken');
+
+  const tokenContext: TokenType = {
+    token,
+    setToken: (token) => {
+      setSession(token);
+    },
+    isLoading,
+  };
+
+  return <TokenContext.Provider value={tokenContext}>{children}</TokenContext.Provider>;
+}

context/UseStorageState.tsx

@@ -0,0 +1,67 @@
+import * as SecureStore from 'expo-secure-store';
+import * as React from 'react';
+import { Platform } from 'react-native';
+
+type UseStateHook<T> = [[boolean, T | null], (value: T | null) => void];
+
+function useAsyncState<T>(
+  initialValue: [boolean, T | null] = [true, null],
+): UseStateHook<T> {
+  return React.useReducer(
+    (state: [boolean, T | null], action: T | null = null): [boolean, T | null] => [false, action],
+    initialValue
+  ) as UseStateHook<T>;
+}
+
+export async function setStorageItemAsync(key: string, value: string | null) {
+  if (Platform.OS === 'web') {
+    try {
+      if (value === null) {
+        localStorage.removeItem(key);
+      } else {
+        localStorage.setItem(key, value);
+      }
+    } catch (e) {
+      console.error('Local storage is unavailable:', e);
+    }
+  } else {
+    if (value == null) {
+      await SecureStore.deleteItemAsync(key);
+    } else {
+      await SecureStore.setItemAsync(key, value);
+    }
+  }
+}
+
+export function useStorageState(key: string): UseStateHook<string> {
+  // Public
+  const [state, setState] = useAsyncState<string>();
+
+  // Get
+  React.useEffect(() => {
+    if (Platform.OS === 'web') {
+      try {
+        if (typeof localStorage !== 'undefined') {
+          setState(localStorage.getItem(key));
+        }
+      } catch (e) {
+        console.error('Local storage is unavailable:', e);
+      }
+    } else {
+      SecureStore.getItemAsync(key).then((value: string | null) => {
+        setState(value);
+      });
+    }
+  }, [key]);
+
+  // Set
+  const setValue = React.useCallback(
+    (value: string | null) => {
+      setState(value);
+      setStorageItemAsync(key, value);
+    },
+    [key]
+  );
+
+  return [state, setValue];
+}